League Rules can be found in the current brochure (PDF document). The remainder of this page explains the workings of some of the less-obvious aspects of the league.
Here's how prizes are awarded at Eastern League races.
The League defines a standard prize list, with prizes in various categories (Open, Vet, Youth etc.) Each rider is eligible for prizes in one or more categories. For example, a junior rider is eligible for Open and Junior prizes. A 55 year old non-elite rider is eligible for Veteran and Vet 50 prizes, but not Vet 60 prizes.
To allocate the prizes, we work down the race result from the top. For each rider, we look at all the prizes that the rider is eligible for that have not yet been awarded. The rider receives the highest value prize that has not yet been awarded. If a rider is eligible for two or more prizes of equal value, they are given the one for the more "prestigious" category. For example, they would be given a Veteran prize rather than a Vet 50 prize, or an Open prize rather than a Junior prize. The process continues until we run out of prizes or riders.
Eastern League race starts are gridded. This is primarily for safety - we want to avoid lots of overtaking in the opening seconds. For this reason, we use a formula that aims to rank riders in their expected finishing position, regardless of whether they're in the League or are regular Eastern riders.
The actual formula is rather long-winded, but in essence:
The system isn't perfect (no system is) but it gets most riders into roughly the right place. If you feel you're being consistently gridded three rows back from where you should be, have a word with the commissaire. If you feel you're one row behind where you should be, your best option is probably to ride more quickly.
Occasionally, a rider may feel the need to complain about something that has happened during a race. Any rider who wishes to make a protest at either a Commissaire's decision, or regarding an incident during the race must do so within 30 minutes of the race result being declared. Any correspondence outside of this time may be noted but not acted upon [British Cycling Rule 16.1.4.7]. Basically, sending an email on the evening after a race is too late for us to help.